There have been numerous designs to provide a light which will illuminate the keyhole of a lockset prior to entry. Recent patents in this area include U.S. Pat. Nos. 5,398,175, 5,179,325, 5,057,957, 4,777,570, 4,467,402, 4,310,873, 4,234,909, 4,078,248, and 3,955,075.
Since part of the lockset is stationary (the housing which is secured to a door) and part of the lockset is rotatable (the knobs/levers), establishing the required connections has proven difficult.